Various, Between Two Points (12K/Line): Over the past four years, Brooklyn's 12K has paralleled the development of the quasi-genre called "microsound," moving from post-techno bleep and pulse to a quieter, more contemplative take on digital sound design. Disc One, featuring lowercase luminaries like Komet, Dan Abrams (Shuttle358) and Kim Cascone, showcases 12K's rhythmic side, coaxing supple grooves out of static and hiss, and finding subtle rhythms in data errors and broken bits. Noto's hermetic tones, born from the confines of the computer, and label head Taylor Deupree's piercing frequencies indicate new levels of austerity, even for this label. But Mikael Stavöstrand's "+" proves just how lush a handful of pixels can be, while Mark Fell, of Mille Plateaux's snd, almost hints at the lithe cadences of UK garage in his brutal atomizations. Disc Two is dedicated to Line, the 12K sound-art imprint curated by Richard Chartier. Here selections from Roel Meekop, Steve Roden and others raise minimalism to a higher level. But as quiet as these works are, they remain busy, with the buzzing of sine waves and the vibrations of cellular sound. Miki Yui fills "Vibra" with a swelling mass of charged particles, while Bernhard Günter's "Kernel Panic" wraps the listening space in layer after layer of uneasy drones. Their subtlety raises the question of whether they're "pieces" at all, or simply the unheard hum of the inner ear, magnified and laid bare.  Philip Sherburne